The purpose of the project is to analyze brainstem and diencephalic neuronal responses to genital stimulation in estrous and anestrous female cats in order to elucidate the neuronal basis of estrogen effects on the cat's behavioral responses to genital stimuli. The experimental approaches to be utilized include chronic recording from brainstem and diencephalic single units and unit clusters in freely-moving cats and single unit recording in acutely-prepared paralyzed animals. In the chronic recording experiments, primary emphasis will be placed upon achieving an understanding of the estrogen-dependent after reaction response to genital stimulation, and in the acute preparations, attention will be placed upon an analysis of the modulation by estrogens of the estrous vocalization. The overall objective of the research is to elucidate, through study of this animal model, the neuroendocrine mechanisms underlying hormone-dependent behavioral responses. BIBLIOGRAPHIC REFERENCES: Hornby, J. B. and Rose, J. D. Responses of caudal brainstem neurons to vaginal and somatosensory stimulation in the rat and evidence of genital-nociceptive interactions. Exp. Neurol., 1976, 51, 363-376. Rose, J. D. Facilitation by estradiol of single unit responses to genital and somatosensory stimuli in the midbrain and pons of the female squirrel monkey. Anat. Rec., 1977, in press.